Open Water Drafting Benefits and Techniques: Swim Smart and Save 30% Energy

Introduction

In the swim leg of a triathlon, or in the middle-to-late stages of the Sun Moon Lake Mass Swim, have you ever noticed that some swimmers seem to be cruising effortlessly, yet they stay right beside you? That is no coincidence—it is the application of a drafting strategy. Drafting is a completely legal technique in open-water swimming, and research shows that effective drafting can reduce water resistance by 20–30%, meaning you only need to expend 70% of the effort at the same speed. This advantage is enough to change the outcome of a race.

The Physics Behind Drafting

When a swimmer moves forward through the water, a low-pressure wake zone forms behind their body. A swimmer who enters this wake zone faces significantly reduced water resistance, allowing the same stroke power to produce greater speed, or maintaining the same speed while expending less energy. This is the same principle as drafting on a bicycle, except it occurs in a three-dimensional body of water.

Effective Drafting Positions:

The most recommended position is the “diagonal behind” position—that is, to the left or right rear of the swimmer ahead, at a distance of about 0.5–1 meter. This position allows you to enjoy part of the wake benefit while maintaining a clear view ahead for sighting.

How to Find a Good Drafting Target?

Criteria for Choosing a Target:

• Slightly faster than you, but no more than 10% faster—too large a gap and you will lose contact; too small and you will not save energy.
• Swims a steady, straight line—a swimmer who drifts badly will make you follow a detour.
• Similar stroke rate to yours, making it easier to match their rhythm.

When to Position Yourself During a Race:

1. 100–200 meters after the start: Once the initial chaos settles and the pack naturally spreads out, this is the best time to observe the speed of swimmers around you and pick a target.
2. Close in on swimmers of similar speed: No need to sprint to catch up—find someone just slightly faster than you and naturally slot in behind them.
3. Switch targets early when you cannot keep up: If you feel like you are chasing hard rather than following easily, the target is too fast and you need to change.

Practical Drafting Techniques

Distance Control:
Being too close risks kicking the feet of the swimmer ahead, which not only affects them but can also disrupt your own rhythm; being too far away loses the drafting benefit. The goal is to maintain a distance where you can “just barely see the ankles of the swimmer ahead”—roughly 0.5–0.7 meters.

Responding to Speed Changes of the Swimmer Ahead:
When the swimmer ahead accelerates or changes course, the drafter needs to react quickly. It is recommended to lift your head every 6–8 strokes to confirm the position of the swimmer ahead, avoiding suddenly losing your drafting target.

Drafting in a Group:
In longer races, a drafting line of 3–5 swimmers may sometimes form. The second position in the line offers the greatest benefit; positions further back see diminishing returns because the disturbed water from multiple swimmers ahead reduces the benefit, and sighting visibility is worse.

Drafting Ethics and Rules

Drafting is completely legal in open-water swimming and the swim leg of triathlons. However, note the following:

• Do not deliberately grab, pull, or obstruct other swimmers—this is a rule violation.
• Ensure there is enough space when overtaking—do not force your way through and cause a collision.
• Respect other swimmers’ space—drafting means using the water flow, not engaging in close-contact harassment.

Practical Advice

• In a mass-participation event like the Sun Moon Lake Mass Swim, do not rush to the front right after the start. Let a group of swimmers of similar speed form naturally, then choose the most suitable drafting target.
• Practice “drafting at a steady pace”: during training, have a partner swim ahead while you follow behind, practicing maintaining a fixed distance without speeding up or slowing down erratically.
• Triathletes should pay special attention: the energy saved in the swim leg should be reserved for the bike and run legs that follow. A drafting strategy can leave you with more energy when you exit the water at T1.

Conclusion

Drafting is one of the most intelligent strategies in open-water swimming. It is not cutting corners—it is the correct application of the laws of physics. Master drafting, and you can swim faster with less energy in the swim leg of the Sun Moon Lake Mass Swim or the Taitung Triathlon, preserving your best condition for the events ahead.

Related Reading

• Olympic-Distance Triathlon Swim Drafting: The Invisible Weapon for Saving Energy
• The Complete Guide to Open-Water Drafting: The Energy-Saving Map of 18% Behind the Feet, 12% at the Hip
• Open-Water Drafting Legal Tactic: The Positioning Science of Saving 8% Energy in Swimming
• Open-Water Drafting Technique: The Energy-Saving Difference Between the Feet and Hip Positions